Positive electrode, lithium air battery including positive electrode, and method of preparing positive electrode

Abstract

A positive electrode includes: a carbonaceous core; a coating layer including an electrolyte-philic organic compound on the carbonaceous core; a lithium salt; and an electrolyte, wherein the organic compound includes an imide functional group.

What is claimed is: 
     
         1 . A positive electrode comprising:
 a carbonaceous core;   a coating layer comprising an electrolyte-philic organic compound on the carbonaceous core;   a lithium salt; and   an electrolyte,   wherein the electrolyte-philic organic compound comprises an imide functional group.   
     
     
         2 . The positive electrode of  claim 1 , wherein the imide functional group comprises a substituted or unsubstituted maleimide group, a substituted or unsubstituted succinimide group, a substituted or unsubstituted phthalimide group, or a substituted or unsubstituted glutarimide group,
 wherein at least one substituent of the substituted maleimide group, the substituted succinimide group, the substituted phthalimide group, and the substituted glutarimide group comprises
 deuterium, a substituted or unsubstituted C 1 -C 30  alkyl group, a substituted or unsubstituted C 3 -C 30  cycloalkyl group, or a substituted or unsubstituted C 6 -C 30  aryl group, wherein at least one substituent of the substituted C 1 -C 30  alkyl group, the substituted C 3 -C 30  cycloalkyl group, and the substituted C 6 -C 30  aryl group comprises
 deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a C 1 -C 30  alkyl group, a C 3 -C 30  cycloalkyl group, or a C 6 -C 30  aryl group, or 
 a C 1 -C 30  alkyl group, a C 3 -C 30  cycloalkyl group, or a C 6 -C 30  aryl group, each substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a C 1 -C 60  alkyl group, a C 3 -C 30  cycloalkyl group, a C 6 -C 30  aryl group, or a combination thereof, or 
 
 a combination thereof. 
   
     
     
         3 . The positive electrode of  claim 1 , wherein the electrolyte-philic organic compound comprising an imide functional group is represented by Formula 1: 
       
         
           
           
               
               
           
         
         wherein, in Formula 1,
 ring A is a C 2 -C 30  heterocyclic group comprising an imide group, 
 R is hydrogen, deuterium, a substituted or unsubstituted C 1 -C 30  alkyl group, a substituted or unsubstituted C 3 -C 30  cycloalkyl group, or a substituted or unsubstituted C 6 -C 30  aryl group, 
 wherein at least one substituent of the substituted C 1 -C 30  alkyl group, the substituted C 3 -C 30  cycloalkyl group, and the substituted C 6 -C 30  aryl group comprises
 deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a C 1 -C 30  alkyl group, a C 3 -C 30  cycloalkyl group, or a C 6 -C 30  aryl group, or 
 a C 1 -C 30  alkyl group, a C 3 -C 30  cycloalkyl group, and a C 6 -C 30  aryl group, each substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a C 1 -C 60  alkyl group, a C 3 -C 30  cycloalkyl group, or a C 6 -C 30  aryl group, 
 or a combination thereof. 
 
 
       
     
     
         4 . The positive electrode of  claim 3 , wherein ring A is a C 2 -C 30  heterocycloalkane ring, a C 2 -C 30  heterocycloalkene ring, a C 2 -C 30  heterocycloalkyne ring, or a C 2 -C 30  heteroaryl ring, each comprising an imide group. 
     
     
         5 . The positive electrode of  claim 3 , wherein R is a C 1 -C 30  alkyl group, a C 3 -C 30  cycloalkyl group, or a C 6 -C 30  aryl group, each substituted with at least one —CF 3  group. 
     
     
         6 . The positive electrode of  claim 1 , wherein the electrolyte-philic organic compound comprising an imide functional group comprises a multiple bond or a conjugated bond. 
     
     
         7 . The positive electrode of  claim 3 , wherein the electrolyte-philic organic compound represented by Formula 1 is Compound 1-1 to 1-9, or combination thereof: 
       
         
           
           
               
               
           
         
       
     
     
         8 . The positive electrode of  claim 1 , wherein a thickness of the coating layer is in a range of about 1 nanometer to about 20 nanometers. 
     
     
         9 . The positive electrode of  claim 1 , wherein a content of the coating layer is in a range of about 5 percent by weight to about 20 weight percent, based on a total weight of the carbonaceous core. 
     
     
         10 . The positive electrode of  claim 1 , wherein the coating layer is continuous or in an island form on the carbonaceous core. 
     
     
         11 . The positive electrode of  claim 1 , wherein the core has a spherical shape, a rod shape, a planar shape, a tube shape, or a combination thereof. 
     
     
         12 . The positive electrode of  claim 1 , wherein the carbonaceous core comprises carbon black, Ketjen black, acetylene black, natural graphite, artificial graphite, expanded graphite, graphene, graphene oxide, fullerene soot, mesophase carbon microbeads, carbon nanotubes, carbon nanofibers, carbon nanobelts, soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, sintered coke, or a combination thereof. 
     
     
         13 . The positive electrode of  claim 1 , wherein the electrolyte comprises an ion-conductive polymer, an ionic liquid, or an organic liquid electrolyte. 
     
     
         14 . The positive electrode of  claim 13 , wherein the electrolyte comprises the ionic liquid and the ionic liquid comprises 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide, diethylmethylammonium trifluoromethanesulfonate, dimethylpropylammonium trifluoromethanesulfonate, diethylmethylammonium trifluoromethanesulfonylimide, methylpropylpiperidinium trifluoromethanesulfonylimide, or a combination thereof. 
     
     
         15 . The positive electrode of  claim 1 , wherein a weight ratio of a weight of the electrolyte to a total weight of the carbonaceous core and the coating layer of the electrolyte-philic organic compound is in a range of about 1:1 to about 5:1. 
     
     
         16 . The positive electrode of  claim 1 , wherein the lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide, LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiNO 3 , or a combination thereof. 
     
     
         17 . A lithium air battery comprising:
 the positive electrode according to  claim 1 ;   a negative electrode capable of intercalating and deintercalating lithium ions; and   a separator between the positive electrode and the negative electrode.   
     
     
         18 . The lithium air battery of  claim 17 , wherein upon charging and discharging of the lithium air battery, the number of cycles in which a discharge capacity is 500 milliampere-hours per gram or greater is 20 or more when charging to a voltage of 2.0 volts versus lithium metal. 
     
     
         19 . A method of preparing a positive electrode, the method comprising:
 providing an electrolyte-philic organic compound comprising an imide functional group;   contacting the electrolyte-philic organic compound and a carbonaceous core to form a mixture; and   heat-treating the mixture at a temperature in a range of from about 100° C. to about 250° C. to prepare the positive electrode, the positive electrode comprising the carbonaceous core and a coating layer comprising the electrolyte-philic organic compound on the carbonaceous core.   
     
     
         20 . The method of  claim 19 , wherein the heat-treating comprises heat-treating for about 10 hours to about 40 hours.